Laser ranging, tracking and designation using 3-D focal planes

ABSTRACT

The present invention tracks or locates small moving objects, or generates a 3-D frame of data by using 3-D focal plane arrays with low laser energy and few mechanically moving parts. The invention may be used to determine the direction of a laser designating a target, for target tracking, used as a 3-D movie/video camera or used to provide data for autonomous navigation.

This application is a continuation of U.S. application Ser. No.12/096,311 filed Sep. 26, 2008, now allowed, which is a US NationalPhase of PCT/US2006/061788 which was filed Dec. 8, 2006, which claimspriority of U.S. Provisional Application 60/748,690, filed Dec. 8, 2005.

FIELD OF THE INVENTION

This invention relates to laser pulse imaging of three dimensionalobjects. In particular it relates to embodiments of such technology fortarget acquisition and tracking, collision avoidance or navigation.

BACKGROUND OF THE INVENTION

The 3-D imaging technology disclosed in Stettner et al, U.S. Pat. Nos.5,446,529, 6,133,989 and 6,414,746 provides the use of a single pulse oflaser light to capture the information and content of a 2-D image alongwith a third dimension depth coordinate; thereby providing the 3-Dcoordinates of object points in its field of view. This has beenreferred to as flash 3-D imaging in analogy with ordinary digital 2-Dcameras using flash attachments for a self contained source of light. Aswith ordinary 2-D digital cameras, the light reflected from an object isfocused by a lens onto the focal plane of the camera, which is dividedinto an array of pixels called a focal plane array (FPA). In the case ofa 3-D camera these pixels are “smart” and can collect data from whichthe time of flight of the laser pulse to the object of interest can becalculated as well as data associated with the returning laser pulseshape and magnitude. Because of the similarity to radar imaging, thelaser light is also referred to as flash ladar. These flash 3-D camerasare an improvement upon designs in which one or more pixels is scannedover the field of view. They eliminate the need for a precisionmechanical scanner, which is costly and high maintenance; since thelocation of the pixels in the focal plane may be automaticallyregistered due to their permanent positions within an array.

An additional virtue of flash ladar is its ability to capture an entirescene in one exposure despite the rapid motion of parts or sections oftargets (such as the rotary blade of a helicopter) or rapid motion ofthe 3D camera's sensor platform. During the time it takes light to reachthe target and return to the sensor, mechanical systems typically do notmove fast enough to cause pixel blurring. A time sequence of 3-D flashladar frames comprises a 3-D movie/video of the scene.

BRIEF DESCRIPTION OF THE INVENTION

The present invention comprises apparatus and methods for flash 3Dsystems adapted for acquisition and tracking system suitable formilitary uses, collision avoidance systems suitable for vehiculartraffic, navigational systems and 3D motion picture systems, the latterbeing particularly suited for the development of video games.

The apparatus of the present invention comprises a laser source, a lens,a 3-D FPA and electronics to control the 3-D FPA, data derived from the3-D FPA and process the data. Each pixel in the 3-D FPA comprisesstructures to convert the light falling on it into an electronic signalwhose magnitude is sampled in time and stored in memory within thepixel. Each pixel also comprises a clock that reports the times at whichthe samples are taken. Different embodiments of the invention specifyvarious pulsed laser sources and optional 2-D sensors. The 2-D sensordata may be used to acquire targets or track targets in two dimensionsfor which the 3-D data may provide the target range to the pixel as athird dimension. The 2-D data may also be overlaid or textured on the3-D data to generate more realistic, higher resolution 3-D movies forhuman viewing.

It is an object of the present invention, in separate embodiments, tolocate or track small stationary or moving objects, to developfull-frame 3-D images, or to locate laser-designated targets with aminimum of laser energy, a minimum of mechanical motion or both.

It is another object of the present invention to provide a systememploying full-frame 3-D images in a collision avoidance system.

It is a further object of the present invention to provide a systememploying full-frame 3-D images in a navigation or a reconnaissancesystem.

It is a still further object of the present invention to provide asystem employing full-frame 3-D images in a 3-D movie/video.

It is still further the object of the present invention to provideapparatus and a method to identify the direction of a laser beamdesignating the platform on which the present invention is placed or tolocate the direction of a laser spot on a distant object.

Among the advantages of this device is the novel use of technologyhaving mechanical simplicity and low energy requirements for operation.The low weight and low volume for the device are additional advantagesand stem from the mechanical simplicity, the low energy requirements orboth. Other advantages and uses of the invention will be apparent tothose skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective drawing of the present invention intended toacquire and track moving objects or to locate objects in its field ofview.

FIG. 2 shows 3-D sensor intended to locate objects in s field of view,and locate the direction of a laser beam falling upon the sensor.

FIG. 3 shows the 3-D sensor electronics and focal plane array of thepresent invention.

FIG. 4 is a diagram of the 3-D focal plane array of the presentinvention.

FIG. 5 is a high sensitivity 3-D focal plane array of the presentinvention, an image tube.

FIG. 6 is a diagram of the unit cell circuitry on the 3-D focal planearray of the current invention.

FIG. 7 is an electronic block diagram of the current invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

When generating a flash image with a 3-D FPA each pixel must receiveenough laser energy so that a 3-D image can be generated. The fartherthe object of interest is from the camera the greater the output laserenergy required. Since for long-range systems, cost and power is relatedto the laser energy, reducing the requirement for laser power is abenefit. If the object of interest is only a few pixels in size, is faraway, and could be anywhere in the entire field of view of the 3-D FPA,it is most economical to narrow the transmitted laser beam to be only afew pixels in width and to scan the laser beam. Since scanning a laserbeam requires only a very small, inexpensive and extremely reliablegalvanometer scanner the present invention replaces the full flash ladarsystem by a cheaper, lower power and sometimes-lower weight and lowervolume Energy-Reduced Flash Ladar System (ERFLS).

In one embodiment a 2-D sensor acquires the object of interest andpasses the 2-D coordinates to the ERFLS for tracking. In anotherembodiment of the invention the laser beam is rapidly scanned to findthe object of interest within a time of concern, as in a collisionavoidance system where the object of interest may be a thin cable orwire. In still another embodiment of the invention, where the targetmotion is not too rapid, the entire image can be built up by scanningthe laser beam over the full field of view. In this latter embodiment,pixel registration is not a problem because all pixels are automaticallyregistered by being part of an array. Pixel registration, however, is aproblem in a system where the pixel is mechanically scanned to obtainthe image. A time sequence of ERFLS 3-D frames amounts to a 3-Dmovie/video of the scene which could be used in platform navigation.

There are situations in which one observer uses a pulsed laser beam todesignate a particular object of interest by projecting a laser “spot”on the object. In one manifestation of this application the laser spot'stwo-dimensional coordinates are determined by a separate distantobserver. Typically the distant observer scans a pixel or a small pixelarray over the full field of view of the system searching for the laserspot. As with other mechanical systems that scan a pixel, this system iscostly and high maintenance. In another embodiment of the presentinvention this scanned mechanical search system is replaced by a 3-DFPA, which takes in the full field of view of the pixel scanner. In amodification of this embodiment a 3-D FPA is used to identify thedirection of laser beam attempting to locate the platform on which the3-D FPA is mounted.

A preferred embodiment is described with reference to the figures wherelike numbers denote the same elements.

A preferred embodiment of the present invention, depicted in FIG. 1, isan acquisition and tracking system. It is comprised of a pulsed lightsource 1, compact scanning mirror system 2, including a scanning mirror5 a, a 3-D sensor 3, a 2-D acquisition sensor 4, and a control computer5 to store and process data. In other embodiments where the presentinvention is used as a collision avoidance or navigation system the 2-Dsensor may or may not be present. In addition where the objects in thefield of view of the 3-D sensor are poor reflectors of the light fromthe pulsed light source 1, the pulsed light source may generate enoughpower so that a cooler 6 is necessary to cool the pulsed light source 1.For those circumstances where a cooler is required the cooler 6 is partof the acquisition and tracking system. Preferably, the light source isa pulsed laser that creates a pulse with a pulse width of a fewnanoseconds. For use with near objects, the invention may only require apulse from a lower energy laser diode as the pulsed light source 1. Thepresent invention may also include a response system 99 to react to theobject being tracked. The light source may include a beam shapingelement 1 a, typically optics or a diffuser or both. The beam shapingelement may be incorporated into the scanning mirror 5 a as one or asystem of electronically controlled mirrors. These latter mirrors may bea Micro-Electro-Mechanical System (MEMS) fabricated with nanotechnology.

The 3-D sensor 3 is shown in FIG. 2 and is comprised of a lens system 7and a 3-D sensor housing 8. Inside the sensor housing 8 is the 3-D FPA10 (see FIG. 3) and 3-D sensor drive and output electronics 9.

FIG. 3 illustrates the 3-D sensor drive and output electronics 9, whichis typically comprised of a drive board 11 and the output and interfaceelectronics board 12. Typically the 3-D focal plane array (FPA) 10 iselectrically and mechanically attached to a drive board 11, whichprovides the clocks and biases Io the Readout Integrated Circuit (ROIC)chip 14 (see FIG. 4) of the 3-D FPA. The drive board 11 may also providethe voltage biases required for the detector array 15 of the 3-D FPA 10.The output and interface electronics board is connected by means of acable 13 or a transmitter or a direct mechanical and electricalconnection to the control computer or computer board 5.

FIG. 4 shows the details of the FPA 10. The FPA 10 is comprised, in oneembodiment, of a light sensitive detector array 15 and an ROIC 14. FIG.4 indicates the detector array 15 and the ROIC chip 14 are divided intopixels 16 with a corresponding pixel 17 b on the detector array 15 and acorresponding pixel 17 a on the ROIC 14 that are electrically connectedby a metallic bump 18. In another monolithic embodiment the lightsensitive detector array 15 and ROIC array 14 chips are combined intoone chip. In one preferred embodiment, the light sensitive detectorarray 15 is a P-intrinsic-N (PIN) or a N-intrinsic-P photodiode or a APD(avalanche photodiode) fabricated on a single, low resistivitysemiconductor chip. In another embodiment, each light sensitive detectorpixel 17 b is incorporated into the readout pixel (or unit cell) 17 aitself in a way known by those familiar with the art. This monolithicdesign eliminates the complexity of two chips (14 and 15) hybridizedwith metallic bumps 18.

FIG. 5 shows an image tube embodiment of the FPA 10, in which the lightsensitive detector array 15 is a silicon detector array and the detectorarray 15 and ROIC array 14 are incorporated into an evacuated enclosurewhere photons P pass through a transparent window 95, interact with thephotocathode 98 of the image, producing photoelectrons e. Thephotoelectrons are accelerated into the detector array 15 by an electricfield E producing an amplified electrical signal by impact ionization inthe detector array. This amplified signal is then indistinguishable,when further processed, from a photon-produced electrical signal in thedetector array. In the case of an image tube, control, timing and biassignals flow through the header of the image tube 97, which iselectrically and mechanically attached, typically by pins 96 to thedrive and output electronics 9. In another image tube embodiment of theFPA 10, a microchannel plate is the electron amplification mechanism andis placed between the photocathode and ROIC 14 hybridized to detectorarray 15, however the detector array 15 is replaced by an anode array.The anode array simply collects the amplified electrical signals fromthe microchannel plate and passes them on through metal bumps 18 to theROIC 14. In another image tube embodiment of the 3-D FPA 10 the imagetube is placed in a magnetic field resulting in a digicon. Image tubes,headers, photocathodes, microchannel plates, anode arrays and digiconsare known to those skilled in the art of low-noise photon-signalamplification.

The electronic circuit 17 c on each ROIC unit cell (pixel) 17 a of theROIC chip 14 is diagrammed on FIG. 6. Each unit cell circuit 17 ccontains an input amplifier 27, a trigger circuit 21 delay circuit 22, acircular selector 19, a count accumulator 23, and several switches 28each connected to its own memory cell. An output amplifier 25 drives thedata in the memory cells 31 out of the unit cell to a chip outputamplifier which drives the data off the ROIC chip 14 and to the driveand output electronics 9. In alternate configurations of the ROIC unitcell 17 a the clock 29 may enter the count accumulator 23 and the countaccumulator 23 drive the circular selector 19. In an alternateconfiguration of the ROIC unit cell circuit 17 c the count accumulator23 and circular selector 19 may be combined. In still another alternatedesign ROIC unit cell 17 a which, does not capture the laser pulse shapethe circular selector 19, switches 28 and memory cells 31 may not bepresent.

In an alternate design of the ROIC chip 14 the unit cell data is notdriven off the chip but driven to an on-chip processor, which processesthe data. The processed data is then driven off the chip. The on-chipprocessor may be a parallel processor so that each row of unit cells hasits own processor. In alternate designs groups of rows may bemultiplexed to their own on-chip processor.

A block diagram of the system electronics is displayed on FIG. 7,composed of the drive and output electronics 9 and the master computer5. The focal plane array 10 receives its power and the bias voltagesneeded to run it from the power component 33. The embedded computer 34,typically a field programmable gate array (FPGA), generates the clocksignals for the focal plane array 10 and the memory 35. These includethe signals to initiate data acquisition, regulate raw data output fromthe focal plane array 10, and set options such as the clock frequency 29and delay time 22. Data from the focal plane array 10 is completely orpartially processed in the embedded computer 34 before being sent to thememory 35 and master computer 5 which may complete the processing, storethe results and display the acquired three dimensional image or activatethe response system 99. In another embodiment all the processing isperformed on the embedded computer 34, with the master computereliminated, and it activates the response system. The master computer 5may permit an operator to communicate with the drive and outputelectronics 9 and, indirectly, the focal plane array 10.

The Acquisition and Tracking System

The acquisition and tracking system 100 operates as follows: The 2-Dsensor 4, typically a visible or infrared sensor, acquires a target,which can be moving with respect to the acquisition and tracking system100. Typical targets are rockets, mortars, rocket propelled grenades,bullets and initial light emissions generated when these targets arefired. The 2-D camera transfers the two-dimensional x,y coordinateposition of the target either directly or by means of the computer 5 orembedded computer 34 to the two-axis scanning mirror system 2 whichrapidly orients its mirror 5 a in coordinates x and y so that a pulse oflight from the pulsed light source 1, through the beam shaping element 1a, reflected from the mirror 5 a will intersect the position of thetarget. The pulse of light emitted from the pulsed light source 1,traveling at the speed of light, intersects and reflects from thetarget. The reflected light is captured by the lens 7 of the 3-D sensor3 and focused on the focal plane array 10 attached to the drive andoutput electronics 9 of the 3-D sensor. The target typically subtendsone pixel 16 for acquisition and tracking but could subtend more thanone, particularly if the embodiment used is for collision avoidance,navigation, reconnaissance or 3-D movies/videos.

The light pulse reflected from the target generates an electricalcurrent in the detector pixel 17 b representative of the pulse shapegenerated by the pulse light source 1. This current passes through themetal bump 18 and into the corresponding ROIC unit cell 17 a. The targetmay modify the pulse shape but processing in the computer 5 or the driveand output electronics 9, embedded computer 34, will account for thepulse shape modification. The current from the detector pixel 17 b isinput to the ROIC unit cell circuitry 17 c in the ROIC unit cell 17 aand amplified by input amplifier 27 and then sampled and stored inmemory cells 31. Only three memory units are shown in FIG. 6 although inthe preferred embodiment many may exist. The sampling is accomplished bythe clock 18, circular selector 19 and switches 28. The circularselector has as many outputs as memory cells 17. At each write clockpulse, the circular selector shifts turning on a separate andindependent switch 28 which connects the input amplifier 27 output toone memory cell 31. After all memory cells have been filled the memorycells are overwritten as new data arrives. Consequently, the memorycells are always filled with the most recently sampled waveform data.The clock period is typically much shorter than the pulse width and sothe pulse shape is captured in the memory cells 31. If the inputamplifier 27 is a transimpedance amplifier the detector 17 b current istransformed to a voltage and the memory cells 31 sample this voltage. Ifthe input amplifier 27 is a current amplifier the detector 17 b currentis amplified and the memory cells 31 integrate this current. If thedetector 17 b signal is voltage the input amplifier 27 can be a voltageamplifier and the memory cells 31 sample this voltage. The circularselector 19 could be a simple sequential shift register but could bebased upon an algorithm and therefore not sequential.

In one preferred embodiment, sampling begins when the light pulse isemitted. The count accumulator 23 starts counting after one completecircular selector cycle and continues incrementing the count with eachsubsequent circular selector cycle. The input amplifier 27 output ismonitored by a trigger circuit 21, typically a Schmitt Trigger, whichoutputs a signal to a delay circuit 22 when the amplifier output 20reaches a pre-specified or drive and output electronics 9 adjustablemagnitude. After a preset, or drive and output electronics 9 adjustable,time delay, the delay circuit 22 stops the circular selector, whichterminates the sampling and counting. The count accumulator 23 countsthe number of times the circular selector has cycled or, in an alternatedesign, counts the number of clock pulses or equivalently the number oftimes the circular selector has shifted. In another preferredembodiment, sampling is begun in all pixels when a signal is input tothe ROIC 14 from the drive and output electronics 9. In another or thesame preferred embodiment, sampling is stopped when a signal is input tothe ROIC 14 from the drive and output electronics 9; this signal can beprogrammed to occur at a specific time. The count accumulator 23 couldbe a simple digital counter but could be based on a algorithm andtherefore not sequential. The algorithm would convert the output of thecount accumulator 23 to the actual count.

In alternate designs the clock pulse is first input to the countaccumulator, which drives the circular selector or the count accumulatorand circular selector are combined into one element. If the countaccumulator 23 drives the circular selector then the trigger circuit 21signal stops the count accumulator.

After the laser pulse has been sampled, the data in all the memory cellsis output by cycling through the circular selector at a lower frequencythan the typical write frequency (the frequency that the data wassampled at). Typically the input amplifier 27 is disconnected from theunit cell circuitry 17 c. The memory cell data is then driven from theunit cell to a chip output amplifier by the unit cell output amplifier25. The chip output amplifier drives the memory cell data to the outputand drive electronics 9, which processes the data and may transfer thedata to the processing and storage computer 5. Similarly, the unit cellcount accumulator 23 is output. This is typically a digital output whenthe clock is a series of pulses but could be analog if the clock is aramp voltage. The memory cell output is typically analog but could bedigital, particularly if the unit cell contained an analog to digitalconverter. Clock signals to output the data are generated in theembedded computer 34 of the drive and output electronics 9. Either theprocessing computer 5 or the embedded computer 34 computes the range tothe target, the third independent coordinate z.

In the acquisition and tracking system 100 embodiment of the currentinvention the x,y position of the target pixel (17 a and 17 b) on the3-D FPA 10 corresponds to the x,y position of the target as determinedby the 2-D sensor 4, although typically the 2-D sensor has more pixelsand its x,y position is more accurate. However, in another embodimentthe detector array 15 of the 3-D FPA 10 is responsive to the ambientlight reflected from the target or to the light emitted by the targetand the 2-D acquisition camera can be eliminated by modifying the ROICchip pixels 17 a so they can integrate target-reflected ambient light ortarget-produced-light as well as capture system 100 generated pulsedlight. In one embodiment eliminating the 2-D sensor the FIG. 6 unit cellcircuit is biased so that one or more of the memory 31 integrate lightat a low frequency typical of integrating sensors during acquisitionmode. Once the target is acquired in 2-D mode and its x,y coordinatesdetermined, the ROIC pixel circuit 17 c is then immediately re-biasedfor 3-D range acquisition to obtain the z target coordinate.

The Moving Target Acquisition and Tracking System

When operating as a moving target acquisition and tracking system 100the x,y coordinate of the moving target is tracked on the 2-D sensor andits corresponding z tracking coordinate is continually found using the3-D sensor. Thus the target track is developed in the embedded computer34 or processing computer 5, or an application specific integratedcircuit (ASIC) replacement of the drive and output electronics 9, andcan predict the origination point and termination point of thetrajectory using algorithms known to experts in the art. The computercan then command a response based on the trajectory computation, in thecase of a moving target, or when acquired in the case of a stationarytarget, from the response system 99. The response system may be acounter missile system, a counter shooter system, or vehicle controlsystem.

Typically the z position of the target in the moving target acquisitionand tracking system 100, and in all other embodiments which associate arange with a pixel 16, is determined both by the time at which the countaccumulator 23 stops and the pulse shape data acquired from the memorycells 31. Only the count accumulator 23 data is necessary if rangeprecision is to be determined within one or a few clock pulses. Rangeprecision of a fraction of a clock pulse can be achieved using the laserpulse shape data from the memory cells 31. Although many differentalgorithms can be used, the most accurate is a comparison of the actuallaser pulse shape with the pulse shape acquired from the memory cells31. Typically the arrival time of the laser pulse or the time of thepeak of the arriving laser pulse is estimated by a matched filteralgorithm or a least squares algorithm. Although these algorithms aretypically applied numerically they can be implemented in circuitry.

The Collision Avoidance System

When operating as a collision avoidance system 100, operation may besimilar to that described for the operation of the moving targetacquisition and tracking system 100: the object to be avoided is firstacquired using the 2-D sensor 4 operation, and the range to the objectof interest results from the acquisition of a laser pulse by the 3-Dsensor 3. However, typically the object of interest in thesecircumstances is defined by many pixels rather than one and may bescanned by a number of laser pulses, or just one, full field of view,laser pulse, to define the 3-D shape. The scanning pattern is typicallydefined or developed in the computer 5 but may be included in thefirmware of an embedded computer 34 located on the drive and outputelectronics 9 or an application specific integrated circuit (ASIC)replacement of the drive and output electronics. In addition thedivergence of the laser pulse may be large enough to illuminate manytarget pixels with a single pulse so that only few laser pulses, or onlyone, are necessary to obtain the full 3-D image. In an alternateembodiment the 3-D focal plane may be re-biased to function as a 2-Dacquisition sensor as well as a 3-D sensor and in still anotherembodiment the 3-D sensor may function as the acquisition sensor. If thesystem is designed so that only one laser pulse is necessary thescanning mirror system 2 may not be present and the laser 1 oriented sothat it illuminates the full field of view of the 3-D sensor 3 typicallyusing a beam expanding element 1 a.

In the embodiment of the collision avoidance or navigation system 100,where the 3-D sensor functions as an acquisition sensor, the 2-D sensor4 is not present and typically the pulse of light from the pulsed lightsource 1 has a beam divergence which illuminates many target pixels;1000 pixels is typical but all pixels may be illuminated by a singlepulse. 3-D image data is transferred to the computer 5 in real time foreach pulse of light and the 3-D image constructed from the scan. Thelaser beam scan will not generally be pixel by pixel but by groups ofpixels until all the pixels in the field of view of the 3-D sensor 3have been acquired. Then the scan will begin again. Typically the scanpattern will be located in the computer 5, in the embedded computer 34,or an ASIC substitute for the drive and output electronics 9. Theembedded computer 34 or the control computer 5 analyzes the 3-D data andactivates a response system 99 to avoid the collision or make navigationadjustments if necessary. Typical response systems include ailerons,steering brakes and accelerators. If power were not an issue the singlelaser flash could illuminate all the pixels in the field of view. If thesystem is designed so that only one laser pulse is necessary thescanning mirror system 2 may not be present and the laser 1 oriented sothat it illuminates the full field of view of the 3-D sensor 3 typicallyusing a beam expanding element 1 a.

The Reconnaissance or Movie Systems

In the embodiments of the reconnaissance (or 3-D movie/video camera)system 100, the 2-D sensor 4 may or may not be present and typically thepulse of light from the pulsed light source 1 has a beam divergencewhich illuminates many or all target pixels; 1000 pixels is typical. Abeam expanding element 1 a, typically a diffuser, may be employed tocontrol the divergence of the laser beam. 3-D image data is transferredto the embedded computer 34 or computer 5 in real time for each pulse oflight and the 3-D image constructed from the scan. Typically the laserpulse repetition frequency is 0.5-10,000 Hz and may depend upon the timedependence and desired time resolution of the scene being captured. Ifthe 2-D sensor is present the object of interest may be acquired withthe 2-D sensor and the 3-D sensor used for target identification (ID). Atypical system of this kind may be a rifle sight where the 2-D sensor isan IR sensor and the control computer 5, under human operator control,displays the 3-D data to the operator who makes the decision to respond.The rifle is the response system in this case. The operator could ofcourse be absent from the reconnaissance system 100 or at a remotelocation. The 2-D sensor data may be overlaid on the 3-D data to enhancethe target recognition. This overlay is sometimes referred to astexturing. The results of panning the 3-D reconnaissance camera over ascene with or without the 2-D overlay, at a frame rate of typically 30Hz, where typically one laser pulse covers the full field of view, is a3-D movie/video, hence 3-D movie/video camera. Overlaying lower spatial(x,y) resolution 3-D FPAs with higher spatial resolution 2-D FPAsincreases the realism or target ID probability. Lower spatial resolution3-D FPAs are desirable if the time resolution of the scene requires fullframes of data since the more 3-D pixels required at one time the higherthe laser energy required. Under those circumstances where full framesof 3-D data are required at high speed the mirror system 2 is not usedand the laser 1 is oriented to illuminate the full field of view.

In another preferred embodiment of the reconnaissance or 3-D movie/videocamera system 100 the beam shaping element 1 a can be varied so that theilluminated field of view of the 3-D sensor 3 can be varied from thefull field of view of the sensor to a few or a single pixel. Thereby thesystem 100 3-D sensor 3 use can be continuously varied from a full fieldof view 3-D imager to a range finder. The smaller the illumination fieldof view, or beam divergence, the longer the range that is possible witha given laser power; with a single pixel illumination field of view thegreatest range can be achieved.

Uses of the Movie System

One particular use of the movie system of the present invention is tocapture three dimensional motion of figures for incorporation into gamemachines. In particular the invention enables a single camera, withoutthe complexities of multiple lens systems employing parallax, to capturethe third dimension of characters participating in a sports event suchas a football game. From the data captured by the 3D camera persons ofskill in the programming art could enable the played back scene to berotated and approached from different geometrical points of view.

The Laser Designation System

In the laser designation embodiments 100 the invention is passive in itsacquisition mode; the laser 1, and mirror system 2 is not used. Neitheris the 2-D sensor 4 typically used. When used as a laser designator theobjective is to locate the x,y position of a target being designated bya pulsed laser beam from an independent, typically not collocated, lightsource. Light scattering off the designated target is focused by theoptics 7 onto the focal plane 10 of the 3-D sensor. One or at most a fewpixels 16 respond to the light. The position of these pixels on the 3-DFPA 10 is determined when the whole array 15 is read out into theembedded computer 34 or the control computer 5 and the computer alertsthe response system 99 to the x,y coordinates of the target. Typicallythe x,y position of the target is defined by the x,y position of thelaser spot on the 3-D FPA 10 and the focal length of the receive optics7. The computer may identify the designation laser using pulserepetition frequency or pulse shape matching algorithms. Under somecircumstances both pulse repetition frequency and pulse shape may beused to identify the designation laser. A typical response system is amissile system.

When the laser designator 100 is being illuminated directly by a laserbeam, light is focused by the optics 7 onto the focal plane 10 of the3-D sensor. One or at most a few pixels 16 respond to the light. Theposition of these pixels on the 3-D FPA 10 is determined when the wholearray 15 is read out into the embedded computer 34 or control computer 5and the computer alerts the response system 99 to the x,y coordinates ofthe laser beam. Typically the x,y position of the target is defined bythe x,y position of the laser spot on the 3-D FPA 10 and the focallength of the receive optics 7. A typical response system is thereconnaissance embodiment 100 of the present invention to identify thelaser source.

When the image tube FPA 10 is used with the 3-D sensor 3 in any of theembodiments, laser light passes through the window 95 and interacts withthe photocathode 98 producing an electron, e. The electron isaccelerated by the internal electric field E to a relatively highenergy, typically measured in KeV, until impact of the electron with thedetector array 15 causes the generation of many electron-hole pairs.Either the electrons or the holes are swept into the ROIC 14, throughthe metal bump 18, by an electric field internal to the detector, andthe process is then the same as for the solid state array depicted inFIG. 4.

The invention claimed is:
 1. A 3D camera system with a field of viewadapted to capture a composite 3D image of a figure of interest withinsaid field of view, the 3D camera system comprising: a computer adaptedto generate a clock signal and an initiation signal to start dataacquisition following the emission of an illuminating light pulse; apulsed light source having a beam shaping element, said pulsed lightsource emitting at least one light pulse illuminating the figure ofinterest within said field of view; a digital memory circuit connectedto said computer and to a 3D sensor; a 2D camera having an overlappingfield of view, and a 2D image output connected to said computer; a 3Dsensor connected to the computer and adapted both to acquire a ladar 3Dimage of said field of view and to store the ladar 3D image in saiddigital memory; wherein said 3D sensor includes: a 3D focal plane array;a sensor housing; a lens system which collects light pulse signalsreflected from said figure of interest and directs said collected lightpulse signals onto the 3D focal plane array, said 3D focal plane arrayincluding: an array of optical detectors having a regular geometricarrangement, positioned in a focal plane of said lens system, and eachdetector converting an incident light pulse signal into an electricalpulse signal; and a readout circuit, including an array of unit cellelectrical circuits with corresponding regular geometric arrangement;wherein each unit cell electrical circuit has an input electricallyconnected to a terminal of a companion optical detector of said array ofoptical detectors, said unit cell electrical circuit adapted to amplifysaid electrical pulse signals and having a trigger circuit adapted todetect the presence of said electrical pulse signal and thereupon toproduce an acquisition termination signal, wherein each unit cellelectrical circuit further includes a unit cell timing circuit initiatedby said initiation signal, said unit cell timing circuit beingterminated by said acquisition termination signal, thereby measuring thetime of flight of a light pulse to the unit cell, said unit cell timingcircuit having a unit cell time of flight output connected to theperiphery of the readout circuit, and the readout circuit having a ladar3D image output comprised of the unit cell time of flight outputs;wherein the computer is adapted to develop a composite 3D image from theladar 3D image output and the 2D image output.
 2. The 3D camera systemof claim 1, wherein the readout circuit includes at least one digitalprocessor.
 3. The 3D camera system of claim 1, wherein the 3D sensorincludes an embedded computer.
 4. The 3D camera system of claim 1,wherein the 2D camera is an infrared sensor.
 5. The 3D camera system ofclaim 1, wherein the timing circuit is a count accumulator driven by aclock.
 6. The 3D camera system of claim 1, wherein the initiation signalis coincident with the emission of an illuminating light pulse from thepulsed light source.
 7. The 3D camera system of claim 1, wherein theunit cell electrical circuit includes an analog to digital converter ofat least one bit.
 8. The 3D camera system of claim 1, wherein thecomputer develops the composite 3D image by employing a method selectedfrom the set consisting of: overlaying, and texturing.
 9. The 3D camerasystem of claim 1, wherein each unit cell electrical circuit includes anelectrical amplifier, said electrical amplifier having an inputconnected through a conductive bump to a terminal of a companion opticaldetector of said array of optical detectors, said electrical amplifierhaving an output connected to a unit cell trigger circuit, the unit celltrigger circuit adapted to detect the presence of said electrical pulsesignal and to produce an acquisition termination signal, and saidelectrical amplifier output further connected to a plurality ofnormally-off switch inputs, and the output of each switch furtherconnected to a memory capacitor, and a logic circuit for selecting acontrol input located on each of the switches, and adapted to turn onsaid switches in a sequence, thereby producing a set of analog samplesof said electrical pulse signal; wherein the unit cell timing circuit isinitiated by said initiation signal following the emission of anilluminating pulse and is terminated by said acquisition terminationsignal, thereby measuring the time of flight of an illuminating pulse tothe unit cell; wherein the unit cell timing circuit further includes aunit cell time of flight output adapted to drive said unit cell time offlight values to the periphery of the readout circuit, and a unit celloutput circuit having an input connecting to each of said memorycapacitors and an output connecting to an analog sample output circuitadapted to drive said analog samples to the periphery of the readoutcircuit.
 10. The 3D camera system of claim 9, wherein the analog sampleoutput is connected to an analog to digital converter.
 11. The 3D camerasystem of claim 9, wherein the logic circuit for selecting and turningon each of the switches in a sequence is a circular selector driven by aclock.
 12. A 3D camera system with a field of view adapted to capturecomposite a 3D image of a figure within said field of view, the 3Dcamera system comprising: a computer adapted to generate a clock signaland an initiation signal to start data acquisition following theemission of an illuminating light pulse; a pulsed light source having abeam shaping element, said pulsed light source emitting at least onelight pulse illuminating a figure of interest within said field of view;an electronically controlled mirror connected to the computer, andadapted to deflect said light pulse throughout the field of view uponinstruction of the computer; a digital memory circuit connected both tosaid computer and to a 3D sensor; a 2D camera having an overlappingfield of view and a 2D image output connected to said computer; a 3Dsensor connected to the computer and adapted both to acquire a ladar 3Dimage of said field of view and to store the ladar 3D image in saiddigital memory; wherein said 3D sensor includes: a 3D focal plane array;a sensor housing; a lens system adapted both to collect light pulsesignals reflected from said figure of interest and to direct saidcollected light pulse signals onto the 3D focal plane array, said 3Dfocal plane array including: an array of optical detectors having aregular geometric arrangement, positioned in a focal plane of said lenssystem, each detector adapted to convert an incident light pulse signalinto an electrical pulse signal; and a readout circuit having an arrayof unit cell electrical circuits with corresponding regular geometricarrangement; wherein each unit cell electrical circuit has an inputelectrically connected to a terminal of a companion optical detector ofsaid array of optical detectors, said unit cell electrical circuitadapted to amplify said electrical pulse signals and having a triggercircuit adapted to detect the presence of said electrical pulse signaland thereupon to produce an acquisition termination signal, wherein eachunit cell electrical circuit further includes a unit cell timing circuitinitiated by said initiation signal, said unit cell timing circuit beingterminated by said acquisition termination signal, thereby measuring thetime of flight of a light pulse to the unit cell, said unit cell timingcircuit having a unit cell time of flight output connected to theperiphery of the readout circuit, and the readout circuit having a ladar3D image output corresponding to the unit cell time of flight outputs;wherein the computer is adapted to develop a composite 3D image from theladar 3D image output and the 2D image output.
 13. The 3D camera systemof claim 12, wherein the readout circuit includes at least one digitalprocessor.
 14. The 3D camera system of claim 12, wherein the 3D sensorincludes an embedded computer.
 15. The 3D camera system of claim 12,wherein the timing circuit is a count accumulator driven by a clock. 16.The 3D camera system of claim 12, wherein the initiation signal iscoincident with the emission of an illuminating light pulse.
 17. The 3Dcamera system of claim 12, wherein the computer develops the composite3D image by employing a method selected from the set consisting of:overlaying, and texturing.
 18. A 3D camera system with a field of viewadapted to capture 3D images of figures within said field of view, the3D camera system comprising: a computer adapted to generate a clocksignal and an initiation signal to start data acquisition following theemission of an illuminating light pulse; a pulsed light source having abeam shaping element, said pulsed light source emitting at least onelight pulse illuminating a figure of interest within said field of view;an electronically controlled mirror connected to the computer, andadapted to deflect said light pulse throughout the field of view; adigital memory circuit connected both to said computer and to a 3Dsensor; a 3D sensor connected to the computer, and adapted both toacquire a 3D image of said field of view and to store the 3D image insaid digital memory; wherein said 3D sensor includes: a 3D focal planearray; a sensor housing; a lens system which collects light pulsesignals reflected from said figure of interest and directs saidcollected light pulse signals onto the 3D focal plane array, said 3Dfocal plane array including: an array of optical detectors having aregular geometric arrangement, positioned in a focal plane of said lenssystem, and each detector converting an incident light pulse signal intoan electrical pulse signal; and a readout circuit, including an array ofunit cell electrical circuits with corresponding regular geometricarrangement; wherein each unit cell electrical circuit has an inputelectrically connected to a terminal of a companion optical detector ofsaid array of optical detectors, said unit cell electrical circuitadapted to amplify said electrical pulse signals and having a triggercircuit adapted to detect the presence of said electrical pulse signaland thereupon to produce an acquisition termination signal, wherein eachunit cell electrical circuit further includes a unit cell timing circuitinitiated by said initiation signal, said unit cell timing circuit beingterminated by said acquisition termination signal, thereby measuring thetime of flight of a light pulse to the unit cell, said unit cell timingcircuit having a unit cell time of flight output connected to theperiphery of the readout circuit, and the readout circuit having a 3Dimage output comprised of the unit cell time of flight outputs; whereinthe computer is adapted to capture three dimensional motion data of saidfigure of interest from the ladar 3D image output.
 19. The 3D camerasystem of claim 18, wherein the captured three dimensional motion datais incorporated into a video game.
 20. The 3D camera system of claim 18,wherein a computer program is adapted to rotate and approach thecaptured three dimensional motion data from different geometrical pointsof view.